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Constant of Proportionality. Vocabulary. Constant: a unique number that stays the same. Variable : placeholder for an unknown number. proportional relationship: is described by ordered pairs that satisfy the equation y = kx where k is a positive constant.
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Vocabulary • Constant: a unique number that stays the same. • Variable: placeholder for an unknown number. • proportional relationship: is described by ordered pairs that satisfy the equation y = kxwhere k is a positive constant. example: y = 2x (1,2);(2,4);(3,6);(4,8) • K: is the constant of proportionality which is the unit rate. (y = kx)
Wildlife conservationists are concerned that the deer population might not be constant across the national forest. The scientists found that there were 144 deer in a 16 square mile area of the forest. In another part of the forest, conservationists counted 117 deer in a 13 square mile area. Yet a third conservationist counted 24 deer in a 216 square mile area of the forest. Do conservationists need to be worried
Does it matter if the deer population is not constant in all areas of the national forest? • What is the population density of deer per square mile? (How many deer per square mile?)
When we find the number of deer per square mile, what is this called? • Unit Rate • How do we know if the relationship between square miles and number of deer is proportional? • The number of square miles can be multiplied by nine to give the number of deer in the specified area.
9 9 • The unit rate of deer per square mile is _____ • The constant of proportionality is ______ • The meaning of the constant of proportionality in this problem is ______________________________________ • Use the unit rate to find the number of deer in 207 square miles. • Use the unit rate to find the number of square miles in which you would find 486 deer There are 9 deer for every square mile 1863 deer 54 square miles
The unit rate and constant of proportionality are the same. They both represent the same number that is the value of the ration of y to x
Brandon came home from school and informed his mother that he volunteered to make cookies for his entire grade level. He needs 3 cookies for each of the 96 students in 7th grade. Unfortunately, he needed them for the very next day! Brandon and his mother determined that they can fit 36 cookies on two cookie sheets.
Is the number of cookies proportional to the number of sheets used in baking? • The constant of proportionality is _____ • What is the meaning of the constant of proportionality?
It took 2 hours to bake 8 sheets of cookies. If Brandon and his mother start baking at 4:00pm, what time will they finish? 8:00 pm
Suzette and Margo want to prepare crepes for all of the students in their French class. A recipe makes 20 crepes with a certain amount of flour, milk, and 2 eggs. The girls know that they already have plenty of flour and milk but need to determine the number of eggs needed to make 50 crepes because they are not sure they have enough eggs for the recipe. • Considering the amount of eggs necessary to make the crepes what is the constant of proportionality? • What does the constant of proportionality mean in the context of this problem? • How many eggs will be needed to make 50 crepes?